Jump to content
HybridZ
JMortensen

Question about dual master cylinders...

Recommended Posts

I'm looking at different options to install dual masters. I know I've discussed all of these here at one point or another, now I'm trying to make a decision.

 

1. Buy a complete Wilwood or Tilton pedal assembly. I'm thinking I'd do the masters in the engine compartment. I don't think this would be terribly difficult to install as it just has to be bolted to the firewall and the appropriate holes drilled, but I've never done it before. One major question I have is what happens to the steering column in this case???? Something like this is what I have in mind: http://www.pitstopusa.com/detail.aspx?ID=1155

http://www.tiltonracing.com/content.php?page=list2&id=4&m=b

 

2. Buy an already modified Datsun pedal box from DP racing. This option is $500 something with masters. It puts the masters inside the car, so if they leak they drip on your shoes and the reservoirs must be remotely mounted.

 

3. Buy John Coffey's new super wazoo dual master setup from http://www.betamotorsports.com. Bolts on, no fabrication, don't even have to remove the pedal box (mine's already out though) and it is $454.95 with no masters and I wouldn't have to screw with the clutch at all. I think this is the nicest option for sure, but I don't have a lot of money.

 

4. Buy a balance bar assembly and attempt to cut up my pedal box and modify it to work. I understand that this isn't all that hard to do if you know what you're doing. I don't know what I'm doing though so this would be an adventure to say the least. Iskone's car has this done to it, and I know tube80z has done it as well, pics of Iskone's car in this thread: http://forums.hybridz.org/showthread.php?t=111465

 

Anyone done #1 or #4 before? Easy, hard? At this point I'm getting a bit tired of big projects and although I've turned the corner and my car is starting to go back together instead of coming further and further apart, the sooner it gets completed the better. That means the cheaper and easier this is the better. I guess I'm trying to find that sweet spot between cheap and easy.

Share this post


Link to post
Share on other sites
Anyone done #1 or #4 before? Easy, hard? At this point I'm getting a bit tired of big projects and although I've turned the corner and my car is starting to go back together instead of coming further and further apart, the sooner it gets completed the better. That means the cheaper and easier this is the better. I guess I'm trying to find that sweet spot between cheap and easy.

 

I did option 4. Not that hard but you need to make sure you get the pedal ratio correct. You can see some shots at http://picasaweb.google.com/tube80z/BrakeUpgrade If these are a little small let me know and I can send you larger versions.

 

Cary

Share this post


Link to post
Share on other sites

I did # 1 using the Wilwood setup. We decided not to mount the reservoirs on the inside of the car due to the potential for spills or leaks but instead, installed them under the cowl grill. The top grill is easy to access because I don't have windshield wipers. There are four screws that hold it in place. Also, this really cleaned up the firewall area in front of the driver's seat.

 

HPIM0556.jpg

Share this post


Link to post
Share on other sites

I did #4 as well. I felt it was a fairly simple, straight foward install. I'll snap some pics tonight as well. Also, I gather by pedal ratio Cary means between the two masters? This is really isn't something you need to be too concerned with during the install, but rather an adjustment after everything is assembled. Also, the remote cable can kit can be used for this. I also found the sleeve needs to be honed out just a bit after welding, or at least mine was distorted enough to where the rod wouldn't slide through.

 

I did run into problems initially with the setup, the front master wasn't retracting far enough, and as the brake fluid swelled, the brakes increasingly stayed on until the car would barely roll anymore. It does address this in the instructions, but I found the pictures/diagrams to be a bit misleading; they seem to be exaggerated just a bit.

 

http://www.tiltonracing.com/ins/98-1250.pdf

Share this post


Link to post
Share on other sites

I plan on going with a reverse-mount, hanging pedal setup from Coleman Racing. With clutch pedal and three aluminum Tilton MCs, price comes out to about $330. http://www.colemanracing.com/catalog/index.php?cPath=29_532 If you just want a brake pedal with dual MCs, price is around $230. http://www.colemanracing.com/catalog/index.php?cPath=29_534 They sell floor and firewall mount setups too (with MCs in the engine bay).

 

I think that by pedal-ratio he actually means the lever arm ratio of the pedal in relationship to the pickup point of the MC pushrod. I'm planning on using around a 6.25:1 ratio.

Share this post


Link to post
Share on other sites
Guest Mike

boodlefoof... reverse-mount MC's... How difficult is it to refill the reservoirs? What if they leak? What is the benefit of using three MC's?

Share this post


Link to post
Share on other sites

Don Oldenburg of DP Racing used to do number 4 for people. All you had to do is send him a pedal box and he would return it with the MCs mounted to the box, under the dash. A number of local guys got tired of waiting for Don to deliver and asked me to duplicate what I had on the ROD.

 

What got built on the ROD way back in 2000 was the result of me trying to fit floor mount and/or hanging Tilton pedals to my car. With the hanging pedals I was uncomfortable mounting them in a car that didn't have a cage with a knee bar. I couldn't figure out how to make the floor mounts work without building a false floor.

 

Unfortunately the price on the setup I sell is a bit high, but I could send out to China, have 10,000 built, and sell them for $39.95 each... :D

Share this post


Link to post
Share on other sites
boodlefoof... reverse-mount MC's... How difficult is it to refill the reservoirs? What if they leak? What is the benefit of using three MC's?

The leak is why I want them in the engine compartment. My friend used remotes on a reverse mount pedal assembly and had a very slow leak and it dripped brake fluid directly onto his shoes, which then made it hard to stop the car because his feet were sliding all over the place. I suppose the advantage of doing the reverse mount is that you gain space in the engine compartment, but I figure this will gain a ton of space vs the stock booster and tandem master config.

 

The benefit of three masters is that you can use different size masters for the front and rear brakes, and the bias is actually proportional. The bias that you get with an adjustable proportioning valve is not really proportional, so if you get max rear braking at slow speeds you end up with rear brakes that don't do much at higher speeds. Likewise if you set it for max rear braking at high speeds it locks up the rear at low speeds. If you want more info on this, click here: http://www.stoptech.com/tech_info/wp_proportioning_valves.shtml

 

If its a street car you're building you probably won't care about anything more than the aesthetics issue, but there is a real difference between the dual masters and adjustable prop valves.

Share this post


Link to post
Share on other sites
With the hanging pedals I was uncomfortable mounting them in a car that didn't have a cage with a knee bar. I couldn't figure out how to make the floor mounts work without building a false floor.

Not a big fan of floor mounted pedals at all. I'm curious though as to why you had trouble with hanging pedals? Is it that they couldn't be mounted sturdily enough? Did you have a rough idea of how you would use a knee bar to brace the pedal assy?

 

I've seen some where they attached a bracket that hooked up to the the column support, similar to the stock pedal box. I think Kipperman's car is done this way.

Share this post


Link to post
Share on other sites
Guest Mike

JON... Thanks for the explanation. So... two MC's are used on the front and one for the rear?

 

For those wanting reverse-mount MC's... it seems logical to mount the proportioning valve inside at arm's reach since the MC's are in the passenger compartment anyway.

Share this post


Link to post
Share on other sites
Guest Mike

SteelToad... I have the market cornered on idiot questions. See post #12.

Share this post


Link to post
Share on other sites
I may sound like an idiot but ....

 

Do you need to run a booster with a setup like the reverse mounted pedals ?

I've never been quite sure about that

No, you generally use a smaller master cylinder than you would use with a booster and you have a better leverage ratio on the pedal, so the booster isn't needed.

 

Mike, the dual master setups come with a balance bar setup, which is an adjustable proportioning valve in it's own right, and this is usually set up on the dash. It's a knob which adjusts the pressure from one master to the other.

Share this post


Link to post
Share on other sites
Also, I gather by pedal ratio Cary means between the two masters? This is really isn't something you need to be too concerned with during the install

 

No by pedal ratio I mean where you put the balance bar. On a car wtih a vacuum booster it needs to go a little higher up the arm. I looked at the tilton pedals and used there leverage ratio when I modded the stock arm (distance from pivot to balance bar and total length of pedal). I have driven a car with the balance bar in the stock location and it requires a lot higher pedal effort to get stopped.

 

Cary

Share this post


Link to post
Share on other sites
I'm curious though as to why you had trouble with hanging pedals? Is it that they couldn't be mounted sturdily enough? Did you have a rough idea of how you would use a knee bar to brace the pedal assy?

 

I had the steel NASCAR approved Tilton forward mount MC pedal assembly. The mount is designed to be bolted to a horizontal surface so my thinking was that the stock pedal box would handle the rear of the mounting surface and a knee bar would be needed to handle the front of the mounting surface. I was concerned that the column mount and dash wouldn't be strong enough because of the amount of material I needed to remove from the stock pedal box to clear the forward mounted MCs.

 

Mike, the dual master setups come with a balance bar setup, which is an adjustable proportioning valve in it's own right, and this is usually set up on the dash. It's a knob which adjusts the pressure from one master to the other.

 

The remote adjuster is an extra cost option for a Tilton balance bar. It may be included in the price of a Wilwood balance bar.

Share this post


Link to post
Share on other sites

Mike, there is just one MC for the front and one for the rear. The third one is for the clutch. ;)

 

As mentioned above, I've never seen a vacuum booster with a dual MC setup. I personally think the dual MC setup gives you better pedal feel and makes it easier to modulate your braking effort. Also don't have to worry about vacuum issues with radical camshafts. Of course, if you want total eye-popping braking... I believe CNC brakes sells a dual MC kit with a hydroboost setup.

 

I personally have to reverse mount the MCs due to my frame design. Either that or scoot the pedal assembly off to one side or another... which I would rather not do.

 

As for adjusting brake bias, I have seen a couple of guys with GT-40 kit cars that have set up a tunable adjustment dial on the center console. I think that reaching down there while moving might be a bad idea.

Share this post


Link to post
Share on other sites
Guest Mike
Mike, there is just one MC for the front and one for the rear. The third one is for the clutch. ;)

:ugg: Oh.....

 

As for adjusting brake bias, I have seen a couple of guys with GT-40 kit cars that have set up a tunable adjustment dial on the center console. I think that reaching down there while moving might be a bad idea.

 

Cockpit Adjustable Proportioning Valve here... http://www.arizonazcar.com/brake.html

 

propv.jpg

Share this post


Link to post
Share on other sites

That's a different kind of prop valve. The one for the dual masters is the big red knob next to the gearshift. pkramer1.jpg

It doesn't attach to the brake line, it changes the bias at the master cylinder pushrod. Here's a description of how it works:

http://www.wilwood.com/Products/005-PedalAssemblies/Pages/techtip/pedaltech.asp

 

You can see that this guy has a prop valve plumbed into the brake line as well. You can super fine tune the brakes by using both types of valves.

Share this post


Link to post
Share on other sites

Is there really two adjustable prop valves in line in the picture above? Someone has really screwed up the balance between the calipers and MC if two adjustable prop valves are needed. Maybe one of those is a line lock used as a rear e-bake?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×